Production of new vat dyestuffs



Patented Mar. 24, 1931 UNITED amusement OFFICE f PAUL NAWIASKY, or LUnwIesHAFnN-oNmn-mn,nNn ULIUs MUELLER, OFYMAZNN- HEIM, GERMANY, nssroNoRs'ro GENERAL ANIILINE WORKS, ING.,.0F NEW YORK,

N. Y., A CORPORATION OI DELAWARE PRODUCTION on NEW VAT'DYESTUFFS No Drawing. Original application filed September 2 2, 192;;sera1 1a.m,39,an ineermaa oetober 5, 1926. Divided and this application filed August 1, 1928. Seria1 No. .297,550.

The present invention relates to the duction of new vat dyestuffs.

The subject-matter of this application has been divided out from our copending application for the production of new vat dyeprostuifs Ser. No. 221,396, filed September 22, i v f 1927, Pat. No. 1,742,317, Jan. 7, 1930.

We have found that valuable new vat dyestufis are produced by treating with alkaline agents the ammobenzanthrone obtainable by reducing the nitrobenzanthrone described in Example 2 of the U. S. Patent No. 876,679. If, for example, the said aminobenzanthrone be fused with alcoholic potash, a brilliant green dyestuft is obtained. Other vat dyestuffs may be obtained by employing other alkaline agents or varying the conditions with regard to proportions, temperature and the like.

Similar valuable vat dyestuffs, which are often identical with the green dyestufi just described are obtained by treating substitution products of the aforesaid aminobenzan-- throne, which contain exchangeable subtituents in the Bad-position, or the N-acylated derivatives thereof with alkaline agents. The temperature employed for the treatment with alkaline agents will generally range between about 120 and 200 C.

The green dyestufis prepared according to the methods above described are transformedby the action of oxidizing agents into brown vat dyestuffs of excellent fastness. The brown dyestuffs may be also be produced on the fibre, by treating the dyeings made with the said green dyestuffs with oxidizing agents such as hypochlorites, fast brown dyeings being produced.

Similar brown vat dyestuffs are also obtained in a simple manner by treating the beforementioned nitrobenzanthrone directly with alkaline agents. The resulting dyestufis may be purified by treatment with oxidizing agents such as hypochlorite.

The following example will serve to further illustrate the nature of the said invention but the invention is not limited to this example. The parts are by weight -sponding probably obtainable according ,to Example 2 of the said. U. 'S. Patent, No; 876,679 are introduced into a melt of alcoholic potash, prepared by heating 50 parts of potassium hydroXid with 50 parts of ethyl alcohol. The temperature is maintained at 120 C. for half an hour, and is then gradually raised to H0 G. the alcohol thereby distilling OE, and the melt is kept at that temperature until the formation of the dyestufi' is completed. The reaction taking place may probably be represented by the following formulae:

In the melt, however, the dyestulf is present in the form of its leuco compound. -When cold, the melt is brought into Water, blown with air in order to precipitate the dyestuff which is then filtered off and dried. The resulting dyestuif dissolves to a red-violet solution in concentrated sulfuric acid and gives fast brown dyeings on cotton from the blue vat. A dyestuff of purer shade is obtained by boiling up the crude dyestufl with hypochlorite. The dyeings furnished by this product change into a reddish orange when chlorinated on the fibre.

lVhat we claim is:

1. The process of producing a new valuable brown vat dyestufl which consists in m treating the nitrobenzanthrone obtainable by treating benzanthrone with nitric acid in boiling glacial acetic acid, with a caustic alkali.

2. The process of producing a new valuable brown' vat dyestuff which consists in treating the nitrobenzanthrone obtainable by treating benzanthrone with nitric acid in boiling glacial acetic acid, with an alcoholic caustic potash melt. a

3. As anew article of manufacture the new valuable v'at dyestufi which dyes cotton from the dark blue vat fast brown shades, dissolves in sulfuric acid to a violet solution with a reddish tinge, and which is obtainable by treating the nitrobenzanthrone obtainableby treating benzanthrone with nitric acid, with an alcoholic caustic potash melt.

In testimony wherof, we aifix our signatures.

' PAUL NAWIASKY. JULIUS MUELLER. 

